Quick Change Artist
Behind that silver colored cast cover on the rear end are a pair of meshing spur gears that can be changed in order to alter the final drive ratio of the rear axle. Its common designation is a “quick change rear end.”
In this setup, rotational power input from the engine+transmission enters at the front of the differential housing as it does for conventional drive axles. But unlike the usual setup, the input shaft bypasses engagement with the ring gear and continues to the back where there is a small gearbox at the rear of the differential housing. That small gearbox has an access cover which is what can be seen in the photo above. Within that gearbox are the ends of two shafts - one from the input shaft and a short one above it that’s connected to the bevel pinion that engages the driving ring gear. Each of those two shafts are fitted with spur gears that mesh together to convert rotary motion from the drive shaft to the driving ring gear. Different sets of spur gears can be used in order to change the final drive ratio but they do need to be matched together in order to yield the desired mechanical ratio and to fit in the fixed distance between the two shafts.
Watch this video for a better explanation:
youtu.be/7fhM8Y3TE14?si=MJTenw7JJrlSDTNf
The car is a 1930 Ford Model A Roadster.
The license plate has been altered for privacy.
Quick Change Artist
Behind that silver colored cast cover on the rear end are a pair of meshing spur gears that can be changed in order to alter the final drive ratio of the rear axle. Its common designation is a “quick change rear end.”
In this setup, rotational power input from the engine+transmission enters at the front of the differential housing as it does for conventional drive axles. But unlike the usual setup, the input shaft bypasses engagement with the ring gear and continues to the back where there is a small gearbox at the rear of the differential housing. That small gearbox has an access cover which is what can be seen in the photo above. Within that gearbox are the ends of two shafts - one from the input shaft and a short one above it that’s connected to the bevel pinion that engages the driving ring gear. Each of those two shafts are fitted with spur gears that mesh together to convert rotary motion from the drive shaft to the driving ring gear. Different sets of spur gears can be used in order to change the final drive ratio but they do need to be matched together in order to yield the desired mechanical ratio and to fit in the fixed distance between the two shafts.
Watch this video for a better explanation:
youtu.be/7fhM8Y3TE14?si=MJTenw7JJrlSDTNf
The car is a 1930 Ford Model A Roadster.
The license plate has been altered for privacy.